First fully adjustable sawmill with precise rapid cut band saw

Abstract

A sawmill includes a band saw mounted on a trolley. The trolley carries the band saw back and forth across the length of a log to cut it into boards. A log supporting table is adjustable to accomodate logs of various size. The trolley rails descend incrementally after each cut to reposition the band saw blade for the next cut. The length of each increment, or board thickness, is user selectable by way of an indexable detent bar and limit switch combination. The thickness across the board is held uniform by a pressurized bellows that maintains the proper blade strain in the band saw blade.

We claim: 
     
       1. A sawmill for cutting a log into boards, comprising: a log supporting table;   a pair of rails running substantially parallel to the length of said table;   a trolley mounted to run along the length of said rails;   a band saw connected to said trolley;   a hydraulic actuated clamp adapted to hold said log fixed with respect to said table;   a hydraulic cylinder connected to vary the relative position of said table to that of said rails   a combination detent bar and a limit switch, one of which is coupled to said rails, said combination defining a first series of incremental changes in the position of said rails, one of the elements of said combination being selectively indexable to further define a second series of incremental changes in the position of said rails, said first and second series of incremental changes corresponding to first and second board thicknesses; and   a valve controlling the extension of said hydraulic cylinder in response to said limit switch such that substantially all relative motion of said rails stops after each incremental change in the position of said rails, thus allowing said band saw to cut said log after each incremental change.   
     
     
       2. The sawmill as recited in claim 1, wherein said limit switch is connected to move with said rail. 
     
     
       3. The sawmill as recited in claim 1, further comprising a manual override switch connected to selectively disable the function of said limit switch, whereby said rail is free to continue travelling after each incremental change in the position of said rails. 
     
     
       4. The sawmill as recited in claim 3 further comprising, an up switch in series with a coil of a first relay, a down switch in series with a coil of a second relay, said second relay coil being in series with said limit switch and said manual override switch. 
     
     
       5. The sawmill as recited in claim 1, wherein said detent bar is rotably indexable to selectively expose one of four rows of marks to said limit switch. 
     
     
       6. The sawmill as recited in claim 1, further comprising a pivotly adjustable slide arm coupling one of the elements of said combination detent bar and limit switch to said rails. 
     
     
       7. The sawmill as recited in claim 1, wherein said log supporting table and said rails are both hydraulically repositionable with respect to a stationary frame. 
     
     
       8. The sawmill as recited in claim 7, further comprising a position indicator connected to indicate the position of said log supporting table. 
     
     
       9. The sawmill as recited in claim 7, wherein said log supporting table and said rails are connected to said frame by way of a plurality of pivotting arms. 
     
     
       10. The sawmill as recited in claim 1, further comprising two wheels adapted to support a band saw blade therearound, a slidable bearing mount connecting said wheels to said trolley with said wheels being slideably adjustable with respect to each other, and a bellows connected to said bearing mount and positioned between said wheels, said bellows being pressurizable to exert opposing forces against said bearing mount to urge said wheels apart in a substantially linear direction, thereby tightening said band saw blade. 
     
     
       11. The sawmill as recited in claim 10, wherein said bearing mount includes at least two telescoping tubes that maintains a preset degree of parallel alignment of said wheels. 
     
     
       12. The sawmill as recited in claim 11, wherein said tubes include a plurality of adjustable gibs to ensure a predetermined linear alignment of said telescoping tubes. 
     
     
       13. The sawmill as recited in claim 10, further comprising a quick connect coupled to said bellows, whereby a source of pressurized gas can be readily disconnected from said bellows to allow unrestrained travel of said bellows with said trolley. 
     
     
       14. A sawmill for cutting a log into boards, comprising: a frame;   a log supporting table connected to said frame by a first plurality of parallel arms that pivot to allow a first hydraulic cylinder to raise and lower said table with respect to said frame;   a hydraulic actuated turn hook protruding through said table and adapted to engage and rotate said log;   a hydraulic actuated clamp adapted to hold said log fixed with respect to said table;   a pair of rails running substantially parallel to said table and connected to said frame by a second plurality of parallel arms that pivot to allow a second hydraulic cylinder to raise and lower said rails independent of any raising and lowering of said table;   a trolley mounted to run along the length of said rails;   a band saw connected to said trolley;   a limit switch connected to respond to at least one position of said pair of rails; and   a valve controlling the extension of said second hydraulic cylinder in response to said limit switch such that substantially all relative motion of said rails stops at said one position to allow said band saw to cut said log.   
     
     
       15. The sawmill as recited in claim 14, further comprising a position indicator connected to indicate the position of said log supporting table. 
     
     
       16. The sawmill as recited in claim 14, wherein said limit switch is part of a combination detent bar and limit switch combination, one of which is coupled to said rails, said combination defining a first series of incremental changes in the position of said rails, one of the clements of said combination being selectively indexable to further define a second series of incremental changes in the position of said rails, said first and second series of incremental changes corresponding to first and second board thicknesses, said valve controlling the extension of said hydraulic cylinder in response to said limit switch such that substantially all relative motion of said rails stops after each incremental change in the position of said rails, thus allowing said band saw to cut said log after each incremental change. 
     
     
       17. The sawmill as recited in claim 16, wherein said detent bar is rotatably indexable to selectively expose one of four rows of marks to said limit switch. 
     
     
       18. The sawmill as recited in claim 16, further comprising a manual override switch connected to selectively disable the function of said limit switch, whereby said rails are free to continue travelling after each incremental change in the position of said rails. 
     
     
       19. The sawmill as recited in claim 18, further comprising an up switch in series with a coil of a first relay, a down switch in series with a coil of a second relay, said second relay coil being in series with said limit switch and manual override switch. 
     
     
       20. The sawmill as recited in claim 14, further comprising a pivotly adjustable slide arm coupling one of the elements of said combination detent bar and limit switch to said rails. 
     
     
       21. The sawmill as recited in claim 14, further comprising two wheels adapted to support a band saw blade therearound, a slidable bearing mount connecting said wheels to said trolley with said wheels being slideably adjustable with respect to each other, and a bellows connected to said bearing mount and positioned between said wheels, said bellows being pressurizable to exert opposing forces against said bearing mount to urge said wheels apart in a substantially linear direction, thereby straining said band saw blade. 
     
     
       22. The sawmill as recited in claim 21, wherein said bearing mount includes at least two telescoping tubes that maintains a pre-adjusted degree of parallel alignment of said wheels. 
     
     
       23. The sawmill as recited in claim 22, wherein said tubes include a plurality of adjustable gibs to ensure a predetermined linear alignment of said telescoping tubes. 
     
     
       24. The sawmill as recited in claim 21, further comprising a quick connect coupled to said bellows, whereby a source of pressurized gas can be readily disconnected from said bellows to allow unrestrained travel of said bellows along with said trolley. 
     
     
       25. A sawmill for cutting a log into boards, comprising: a log supporting table;   a hydraulic actuated clamp adapted to hold said log fixed with respect to said table;   a pair of rails running substantially parallel to the length of said table;   a trolley mounted to run along the length of said rail;   a hydraulic cylinder assembly connected to vary the relative positions of said table and said rails with respect to each other;   two wheels adapted to support a band saw blade therearound;   a slidable bearing mount connecting said wheels to said trolley with said wheels being slideably adjustable with respect to each other;   a bellows connected to said bearing mount and positioned between said wheels, said bellows being pressurizable to exert opposing forces against said bearing mount to urge said wheels apart in a substantially linear direction, thereby tightening said band saw blade;   a limit switch connected to respond to at least one position of said pair of rails with respect to said table; and   a valve controlling the extension of said hydraulic cylinder in response to said limit switch such that substantially all motion of said table stops at said one position to allow said band saw blade to cut said log.   
     
     
       26. The sawmill as recited in claim 25, wherein said bearing mount includes two rigid H-frame assemblies each having at least two telescoping tubes that maintain a pre-adjusted degree of parallel alignment of said wheels. 
     
     
       27. The sawmill as recited in claim 26, wherein saw tubes include a plurality of adjustable gibs to ensure a preadjusted linear alignment of said telescoping tubes. 
     
     
       28. The sawmill as recited in claim 25, further comprising a quick connect coupled to said bellows, whereby a source of pressurized gas can be readily disconnected from said bellows to allow unrestrained travel of said bellows with said trolley. 
     
     
       29. The sawmill as recited in claim 25, wherein said log supporting table and said rails are both hydraulically repositionable with respect to a stationary frame. 
     
     
       30. The sawmill as recited in claim 29, further comprising a position indicator connected to indicate the position of said log supporting table. 
     
     
       31. The sawmill as recited in claim 29, wherein said log supporting table and said rails are connected to said frame by way of a plurality of pivoting arms. 
     
     
       32. The sawmill as recited in claim 25, wherein said limit switch is part of combination detent bar and limit switch combination, one of which is coupled to said rails, said combination defining a first series of incremental changes in the position of said rails, one of the elements of said combination being selectively indexible to further define a second series of incremental changes in the position of said rails, said first and second series of incremental changes corresponding to first and second board thicknesses, said valve controlling the extension of said hydraulic cylinder in response to said limit switch such that substantially all relative motion of said rails stops after each incremental change in the position of said rails, thus allowing said band saw to cut said log after each incremental change. 
     
     
       33. The sawmill as recited in claim 32, wherein said detent bar is rotatably indexable to selectively expose one of four rows of marks to said limit switch. 
     
     
       34. The sawmill as recited in claim 32, further comprising a manual override switch connected to selectively disable the function of said limit switch, whereby said rails are free to continue travelling after each incremental change in the position of said rails. 
     
     
       35. The sawmill as recited in claim 34, further comprising an up switch in series with a coil of a first relay, a down switch in series with a coil of a second relay, said second relay coil being in series with said limit switch and said manual override switch. 
     
     
       36. The sawmill as recited in claim 32, further comprising a pivotly adjustable slide arm coupling one of the elements of said combination detent bar and limit switch to said rails.